Phosphorus-Silica Sol-Gel Hybrid Coatings for Flame Retardant Cotton Fabrics

This work investigates the use of organic-inorganic sol-gel coatings based on silica and phosphorous com- pounds for providing cotton fabrics with flame retardant features. To this aim, diethylphosphatoethyltri- ethoxysilane precursor was employed for the synthesis of several sols in combination with different chem- ical additives. Sols were reacted with azo-based compounds and repeatedly applied onto the cellulosic substrate in a multilayer assembly, aiming at assessing the effect of the concurrent presence of Si, P and N on the overall fire behaviour of the fabric. In order to evaluate the flame retardancy of treated cellulosic fab- rics, flammability tests were carried out. The obtained results showed that the phosphorus-silica coating is able to promote the formation of a stable char that acts as insulator barrier. Finally, an additive P-N effect of the ceramic oxide coating in terms of increased residue and decreased heat release rate and total burning time was observed in cone calorimetry tests.